/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    MultipleClassifiersCombiner.java
 *    Copyright (C) 2004 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.classifiers;

import weka.core.Capabilities;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.Utils;
import weka.core.Capabilities.Capability;

import java.util.Enumeration;
import java.util.Vector;

/**
 * Abstract utility class for handling settings common to meta classifiers that
 * build an ensemble from multiple classifiers.
 * 
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision: 5905 $
 */
public abstract class MultipleClassifiersCombiner extends Classifier {

	/** for serialization */
	private static final long serialVersionUID = 2776436621129422119L;

	/** Array for storing the generated base classifiers. */
	protected Classifier[] m_Classifiers = { new weka.classifiers.rules.ZeroR() };

	/**
	 * Returns an enumeration describing the available options
	 * 
	 * @return an enumeration of all the available options
	 */
	public Enumeration listOptions() {

		Vector newVector = new Vector(1);

		newVector
				.addElement(new Option(
						"\tFull class name of classifier to include, followed\n"
								+ "\tby scheme options. May be specified multiple times.\n"
								+ "\t(default: \"weka.classifiers.rules.ZeroR\")",
						"B", 1, "-B <classifier specification>"));

		Enumeration enu = super.listOptions();
		while (enu.hasMoreElements()) {
			newVector.addElement(enu.nextElement());
		}
		return newVector.elements();
	}

	/**
	 * Parses a given list of options. Valid options are:
	 * <p>
	 * 
	 * -B classifierstring <br>
	 * Classifierstring should contain the full class name of a scheme included
	 * for selection followed by options to the classifier (required, option
	 * should be used once for each classifier).
	 * <p>
	 * 
	 * @param options
	 *            the list of options as an array of strings
	 * @exception Exception
	 *                if an option is not supported
	 */
	public void setOptions(String[] options) throws Exception {

		// Iterate through the schemes
		Vector classifiers = new Vector();
		while (true) {
			String classifierString = Utils.getOption('B', options);
			if (classifierString.length() == 0) {
				break;
			}
			String[] classifierSpec = Utils.splitOptions(classifierString);
			if (classifierSpec.length == 0) {
				throw new IllegalArgumentException(
						"Invalid classifier specification string");
			}
			String classifierName = classifierSpec[0];
			classifierSpec[0] = "";
			classifiers.addElement(Classifier.forName(classifierName,
					classifierSpec));
		}
		if (classifiers.size() == 0) {
			classifiers.addElement(new weka.classifiers.rules.ZeroR());
		}
		Classifier[] classifiersArray = new Classifier[classifiers.size()];
		for (int i = 0; i < classifiersArray.length; i++) {
			classifiersArray[i] = (Classifier) classifiers.elementAt(i);
		}
		setClassifiers(classifiersArray);

		super.setOptions(options);
	}

	/**
	 * Gets the current settings of the Classifier.
	 * 
	 * @return an array of strings suitable for passing to setOptions
	 */
	public String[] getOptions() {

		String[] superOptions = super.getOptions();
		int current = 0;
		String[] options = new String[superOptions.length
				+ m_Classifiers.length * 2];
		for (int i = 0; i < m_Classifiers.length; i++) {
			options[current++] = "-B";
			options[current++] = "" + getClassifierSpec(i);
		}
		System.arraycopy(superOptions, 0, options, current, superOptions.length);
		return options;
	}

	/**
	 * Returns the tip text for this property
	 * 
	 * @return tip text for this property suitable for displaying in the
	 *         explorer/experimenter gui
	 */
	public String classifiersTipText() {
		return "The base classifiers to be used.";
	}

	/**
	 * Sets the list of possible classifers to choose from.
	 * 
	 * @param classifiers
	 *            an array of classifiers with all options set.
	 */
	public void setClassifiers(Classifier[] classifiers) {

		m_Classifiers = classifiers;
	}

	/**
	 * Gets the list of possible classifers to choose from.
	 * 
	 * @return the array of Classifiers
	 */
	public Classifier[] getClassifiers() {

		return m_Classifiers;
	}

	/**
	 * Gets a single classifier from the set of available classifiers.
	 * 
	 * @param index
	 *            the index of the classifier wanted
	 * @return the Classifier
	 */
	public Classifier getClassifier(int index) {

		return m_Classifiers[index];
	}

	/**
	 * Gets the classifier specification string, which contains the class name
	 * of the classifier and any options to the classifier
	 * 
	 * @param index
	 *            the index of the classifier string to retrieve, starting from
	 *            0.
	 * @return the classifier string, or the empty string if no classifier has
	 *         been assigned (or the index given is out of range).
	 */
	protected String getClassifierSpec(int index) {

		if (m_Classifiers.length < index) {
			return "";
		}
		Classifier c = getClassifier(index);
		return c.getClass().getName() + " "
				+ Utils.joinOptions(((OptionHandler) c).getOptions());
	}

	/**
	 * Returns combined capabilities of the base classifiers, i.e., the
	 * capabilities all of them have in common.
	 * 
	 * @return the capabilities of the base classifiers
	 */
	public Capabilities getCapabilities() {
		Capabilities result;
		int i;

		if (getClassifiers().length == 0) {
			result = new Capabilities(this);
			result.disableAll();
		} else {
			result = (Capabilities) getClassifier(0).getCapabilities().clone();
			for (i = 1; i < getClassifiers().length; i++)
				result.and(getClassifier(i).getCapabilities());
		}

		// set dependencies
		for (Capability cap : Capability.values())
			result.enableDependency(cap);

		result.setOwner(this);

		return result;
	}
}
